We have been setting up programs in Decision Analysis with the aid of a computer using LISP. During the coming year our plan is to expand our program in the management of Hodgkin's disease by the use of decision analysis and to develop further a program in non Hodgkin's lymphoma as well as one in the management of pulmonary infiltrate in the immunosuppressed patients. In the Hodgkin's program, only the fine details remain. We shall make an effort to obtain more data on the rarer combinations of manifestations and also update our utilities on the more traditional means of treatment as well as the newer modes especially combined modality. An effort will be made to equate disutilities other than mortality. We are determining thresholds for therapeutic decisions and in this way characterizing patients according to indicated therapy. The program that we are developing in non Hodgkin's lymphoma is also in LISP. The disease is described primarily by distinguishing favorable and non-favorable histologies and by a description of specific locations of involvement rather than by an expression of stage. Data on treatment choices are obtained from the literature. Patient material will be derived from our own and other hospitals and from the literature. The model on management of pulmonary infiltrate is designed to consider multiple techniques of diagnosis and treatment in order to determine the best course for individual presentation. We are also investigating the possibility of developing algorithms for various combinations of findings.